I'm guessing they are hard to see. The Rabbit Sheriff gets folks all the time on camera trying to kill the fake deer they put out. I'm sure LE's is just as well or better hid.
I just always assume there might be a camera around and act accordingly. As far as I know, none of my plants have ever been found by LE. Now sorry ass dudes who I thought were my friends are a different story. Unless you are growing with your buddy, don't show him what you are doing. If you do, and they do get ripped, you will always wonder if it was him. That is not good for a friendship.